The present invention relates to a multi-stage forming machine with combined tool blocks.
In conventional multi-stage forming machines, the removal, fastening and setting of tools requires the loosening or screwing in of screws, so that a tool change normally takes around an hour or more. Since the forming machine is out of operation during this time, this entails a considerable loss in productivity. Therefore, forming machines which allow a faster tool change have been developed.
DE-A-197 22 228 discloses a multi-stage forming machine in which each tool is arranged in a tool cartridge which is held in the forming machine by means of a clamping device. The securely clamped tool cartridges can be exchanged relatively quickly as and when required, so that the downtime of the forming machine can be reduced considerably. However, a tool change still takes a comparatively long time, since the fine setting of the distance between two opposite interacting tools is performed on the forming machine.
EP-B-0 354 428 describes a multi-stage forming machine which comprises a first combined tool block, with for example five female-die blocks, fitted on a fixed machine body, and a second combined tool block, with for example five male-die blocks, fitted on a press slide which can be moved back and forth in the direction of the said first combined tool block. The combined tool blocks are exchangeable as a whole and can be set outside the forming machine. To obtain adequate clamping, the combined tool blocks are screwed to the machine body or press slide. This has the disadvantage that quick changing of combined tool blocks is not possible, since the operating personnel have to work from the outside using auxiliary tools.
In view of the disadvantages of the previously known forming machines described above, the invention is based on the following object. It is intended to provide a multi-stage forming machine of the type mentioned at the beginning in which the downtime of the forming machine when changing tools can be reduced considerably with respect to comparable forming machines of the prior art.
The essence of the invention is that a multi-stage forming machine comprises a first and second combined tool block, of which at least one has at least one clamping lug, by which it is suspended, by means of a clamping cam fitted directly or indirectly on a fixed machine body or on a press slide, directly or indirectly from above on the machine body or on the press slide. The clamping lug and the clamping cam are designed in such a way that the dead weight of the combined tool block and/or a clamping force acting in the vertical direction on the combined tool block produces a resilient clamping together of the combined tool block and the machine body or press slide in the horizontal direction. The first and second combined tool blocks have interacting individual tool blocks and are respectively fitted on the fixed machine body and the press slide, which can be moved back and forth in the direction of the first combined tool block.
The suspending of the combined tool block by clamping lugs directly or indirectly on the machine body or on the press slide makes it possible for the combined tool block to be fitted and removed quickly, since it is possible to dispense with screwing. The necessary clamping of the combined tool block to the machine body or press slide is produced by the clamping lug and the clamping cam, which partially deflect the dead weight of the combined tool block and/or a clamping force acting in the vertical direction on the combined tool block into a horizontal clamping force. The clamping has the effect of prestressing the clamping lug in such a way that it is additionally loaded only insignificantly by production-related forces on the combined tool block, as a result of which it is fatigue-resistant. Any clamping device can be arranged outside the tool space, so that it does not take up any space in the latter. The exchanging of an entire combined tool block allows the fine setting of the distance between two opposite interacting individual tool blocks outside the forming machine, while the latter can continue to be operated with the old combined tool block. The downtime can in this way be restricted to the removal of the old combined tool block and the actual fitting of the new combined tool block.
Normally, both combined tool blocks are provided with at least one clamping lug and are suspended directly or indirectly on the machine body or press slide, but it is also conceivable in principle for one of the combined tool blocks to be fastened in some other way.
In a first advantageous design variant, the said at least one clamping lug is arranged in the upper edge region of the combined tool block and at least one further clamping lug is arranged in the lower edge region of the combined tool block and is suspended by means of a further clamping cam from above directly or indirectly on the machine body or on the press slide.
In a second advantageous design variant, the said at least one clamping lug is arranged in the upper edge region of the combined tool block and at least one downwardly projecting clamping cam is arranged in the lower edge region of the combined tool block and is pushed into an upwardly open clamping lug fitted directly or indirectly on the machine body or on the press slide.
These two design variants make it possible for the combined tool block to be clamped uniformly at the top and bottom.
The clamping lug or lugs and/or the clamping cam or cams advantageously has or have a bearing face for the assigned clamping cam or clamping lug, which face is inclined with respect to the vertical and is preferably curved, so that when a vertically downwardly directed force is exerted on the combined tool block the clamping lug or lugs is or are bent outwards by the assigned clamping cam or cams. The resilient bending of the clamping lug or lugs allows a high prestressing to be produced in the horizontal direction, which provides a secure, clamped fastening of the combined tool block, counteracts the development of fretting corrosion and makes it unnecessary for the contact surfaces to fit one another absolutely exactly. The curving of the bearing face prevents edge pressure from occurring.
A plurality of clamping lugs are advantageously arranged in the upper edge region of at least one of the two combined tool blocks and/or a plurality of downwardly projecting clamping cams are advantageously arranged at intervals next to one another in the lower edge region of this combined tool block. As a result, the combined tool block can be supported and clamped over a wide area.
The combined tool block with clamping lugs or at least one of the combined tool blocks with clamping lugs advantageously has at least one stop which rests from above on a stopping face outside the combined tool block. The combined tool block is thus accurately positioned vertically during suspension and thereby defines the maximum clamping force.